Shin exerciser



FIG. 1 is a perspective view of a shin exerciser embodying my new design;

FIG. 2 is a bottom view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a side view thereof, the opposite side being a mirror image thereof; and,

FIG. 6 is a rear view thereof.

The broken lines in FIG. 1 showing a foot and leg illustrate environmental structure and form no part of the claimed design. 

The ornamental design for a shin exerciser, as shown and described. 